Rvalue references

From the C++11 FAQ, section on rvalue references, about a simple incrementation function incr:

If that incr(0) were allowed either some temporary that nobody ever saw would
be incremented or - far worse - the value of 0 would become 1. The latter
sounds silly, but there was actually a bug like that in early Fortran
compilers that set aside a memory location to hold the value 0.